Association of Bacteria and Viruses With Wheezy Episodes in Young Children: Prospective Birth Cohort Study

PURPOSE OF THE STUDY.

Viral infections have been consistently associated with wheezing episodes, but no studies have suggested a role for bacterial infection. This study evaluated the association between wheeze in young children and the presence of bacteria in the airways.

STUDY POPULATION.

Infants (N = 411) from the Copenhagen Prospective Study on Asthma in Childhood with a maternal history of asthma were recruited at 4 weeks of age. Exclusion criteria were premature birth (<36 weeks' gestation), history of mechanical ventilation, congenital disease, or respiratory tract symptoms.

METHODS.

Participants were prospectively examined for common airway pathogenic bacteria and viruses from the ages of 4 weeks to 3 years. The children visited the research clinic every 6 months and as needed for acute respiratory tract symptoms. Asthma-like symptoms and treatment were recorded in diary cards. Hypopharyngeal aspirates were obtained for routine bacterial cultures, and nasopharyngeal aspirates were obtained for virus identification.

RESULTS.

A total of 984 samples (361 children) were analyzed for bacteria, 844 (299 children) were analyzed for viruses, and 696 (277 children) were analyzed for both viruses and bacteria. Colonization shifted from a majority having Staphylococcus aureus in the first months of life to later having Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Wheezy episodes were significantly associated with these 3 pathogens (odds ratio [OR]: 2.9 [95% confidence interval (CI): 1.9–4.3]; P < .001). Wheezy episodes were significantly associated with viral infection (OR: 2.8 [95% CI: 1.7–4.4]; P < .001). The association was unaffected by bacteria as a covariate and with no significant interactions.

CONCLUSIONS.

Acute wheezy episodes in children up to the age of 3 years were significantly associated with bacterial infection. This association was independent of viral infection, which suggests that bacteria might contribute independently.

REVIEWER COMMENTS.

This is the first prospective clinical cohort study that used standard bacterial cultures and sensitive molecular methods for virus detection, and the results suggest that bacteria might contribute to wheezing episodes in children at high risk. Interventional strategies geared toward these microorganisms might be useful to further our understanding of wheezing and asthma development in these children. Given the paucity of information on evidence-based strategies in young children for treating wheezing episodes, clinical trials for evaluating antimicrobial agents and other interventions for wheezing episodes should be considered and are currently being evaluated among large clinical trial networks.

Subjects

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